Friction disk rings are typically used in vehicles, e.g., race cars, air plane landing gear, off-road vehicles, and passenger automobiles, as components of brakes and clutches. Well known friction disk rings are usually fabricated from "papers" composed of randomly oriented fibers, e.g. kevlar fiber, carbon fiber, cellulose fiber, and others, resin binder, recycled materials, and filler, or the disk rings can also be made of woven (i.e. nonrandomly oriented) cloth using various fiber materials. The size of these friction disk rings varies from a few inches to a few tens of inches in outer diameter (OD).
Due, at least in part, to the manufacturing process and raw material cost, carbon-fiber cloth is expensive. Carbon-fiber cloth is made by spinning liquid polymeric precursors, e.g., poly-acrylyl-nitrile (PAN) and mesophase pitch, into a fibrous form. The fiber is woven into cloth. The cloth is then oxidized at about 200.degree. C. and pyrolyzed at about 1000.degree. C. for a few hours. All of the organic volatiles burn up, leaving pure carbon-fiber cloth.
Carbon-based friction disks are generally made by densifying porous fibrous preforms. Such preforms can be made by either stitching multiple layers of carbon-fiber cloth or by hot pressing multiple layers of carbon-fiber cloth along with thermal-set resin binder followed by a pyrolysis process at elevated temperatures. The preforms can then be densified with carbon vapor deposition (CVD) which is thought to be an advantageous form of carbon use in friction surfaces. However, stitching carbon fiber cloth is thought to be advantageous because the carbon-fiber used to stitch layers of cloth together is generally oriented perpendicular to the outer exposed friction surface. This orientation allows the fibers to conduct heat away from the exposed friction surface for better wear.
Known methods of producing friction disks suffer from a very low materials utilization rate. That is, there is a high waste of sheet or cloth materials as currently utilized in the field of friction disk fabrication. For example, if 1-ply rings with ID of 4.175 in. and OD of 4.98 in. are cut from a rectangular sheet, there will be approximately a 73% waste of material. In the automotive transmission industry, friction paper waste can be as high as about 80%-90%.
Accordingly, it would be desirable to provide a method of fabricating a friction disk ring that substantially reduces, or eliminates wasted friction paper or cloth. It also would be desirable if the method of fabricating could be automated, and was capable of producing practically any size disk ring. Further, it would be desirable to provide a friction disk ring having grooves and patterns being symmetric with respect to the radial center of the disk ring.